Binaural system of blind landing



June 8, 1937. n, BA SETT 2,083,494

BINAURAL SYSTEM OF BLIND LANDING Filed July 12, 1933 2 Sheets-Sheet l lI" 1 I. lNvEN oR I" 1 I f ?E5TO'A/-/E 51 759577,

H15 ATTOFNEY.

Filed July 12, 1933 2 Sheets-Sheet 2 INVENTOR D m N m 0 A T 5 I w H DPatented June 8, 1937 UNITED STATES PATENT OFFICE BINAURAL SYSTEM OFBLIND LANDING Preston R. Bassett, Rockville Centre, N. Y., as-

signor to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporationof New York Application July 12, 1933, Serial No. 680,019

6 Claims. (Cl. 177-352) Thisinvention relates to the art of landingairter 20 is shown as located adjacent the approach planes at an airportunder adverse atmospheric boundary 3 of the field- It Will he understoodconditions, such as in fog or heavy snow when that the beacon may bemade portable so as to the ground is concealed until almost reached.change ts p o i respect to the Wind- Such landings are usually referredto as blind When the airplane ne s h field sooner, if 5 landings. I amaware that elaborate radio condesired, the aviatorpicks up thedirectional radio trolled blind landing systems have be n w rked beaconand fiies toward the same preferably, out involving a number of specialradio receivers but not necessarily, at a predetermined altitude andother instruments on the aircraft, in addiknown to the operators at thefield- I have shown tion to their present standard equipment, butmounted ad'jacentsaid beacon a sound locator 10 aside from thecomplications introduced, such 4 pr fer y Operating on e. binaural Dextra equipment adds weight and expense and civic. A convenientarrangement it to mount is only used a very few times a year. Accordingboth on a trailer truck 5 so that they may be to my invention, I proposeusing only standard moved to any desired position on the field orinstruments and radio means on the aircraft from field to field. Saidsound locator may be which include an altimeter, an indicator (visible acomplete binaural device in both azimuth and or audible) for enablingthe operator to fly toelevation, such as shown in an Operator ward thesource of a directional radio beam, and being employed for each or itmay be simplified a two-way radio telephone sending and receivfor thisparticular 2O ing set (or at least the receiving end of the same). In 3e listener at the helmetv 5 Operates According to my system I propose toutilize a the hand-wheel 1 to turn the device in azimuth radio beaconproducing a vertical radiating direca d listens through the horns 8 and9 spaced in tional beam for bringing in the craft along a prea imuth,while the, listener through the helmet t mined course but supplement thesame by Hi operates the elevation handwheel II to turn means of abinaural sound locator located at the the elevation horns and Accordingto y 25 airport which can determine with fair accuracy sys heWeVer, a ep binaulel unit is not the position of the craft from the airport, wereneeded since the airplane may be assumed to by providing the necessaryinformation for dee approaching along t known radio. beam and terminingwhen the craft should start its descent. hence said unit may be turnedin the direction If, for instance, the aircraft is approaching at a ofthe radio transmitter either by hand or auto- 30 predetermined altitudealong the radio beacon maticallyly the elevation horns heed course andthe sound locator is set at a prebe used, therefore, to determine eangle determined angle of elevation, the point at which elevation Asubtended by the C It Will readily the aircraft crosses the angle inelevation at b Se n that if t angle A and the altitude H are which thesound locator is pointing, can readily known, then the Point P at whichthe aircraft 35 be etected by binaural methods. The li te r isdetermined and the distance of the craft from can then at thisinstantnotify the aviator by the sound locator is known. Therefore; n radiotelephone or other signal to start his downhe ang A s reached, aircraftmay be si ward glide to the airport. If the sound locator nalled o d cnd at a predetermined gliding 40 and radio beacon transmitter arelocated adjaangle B ol ac g t angle A, the aviator 40 cent the forwardend of the field, the gliding anwould ordinarily be informed by radio bythe' gle may be so arranged as to bring the aircraft st e at the helmet0 t at h s craft is lldirectly over the radio transmitter, at which timep ch ng the Point Where he should Start his the signals will ceasetemporarily so' that the descent. a h an e f glide s given to himaviator will know he is nearing the ground. also, so that On being otfie descend, he 45 According to the drawings immediately starts hisglide to thereby bring his v Fig. 1 shows diagrammatically onearrangecraft prop y pon the fie dment of my invention at an airport. Asimple method of determining the point P Fig. 2 shows a slightlydifferent arrang m t, ,is to fix the horns in elevation at such anangle.

Fig. 3 shows a view of a typical binaural sound A that the aircraft willdescend along the line 50 locator for-both azimuth and elevation search-L at its gliding angle G to brin it Over the ing. beacon and on to therunway 2 in the proper Referring first to Fig. 1, a typical landingfield position. If the horns are set at this altitudeh is shown at I,one of the runways being at 2. In the listener can readily determinepoint P, at

this instance adirectional radio beacon transmitwhich point the mainvolume of sound shifts 55 from one ear to the other. The listenerpreferably has a microphone l of a radio transmitter T strapped to himand when this sound shift occurs he tells the aviator immediately bywireless- 5 telephone or other signal to descend at a predeterminedgliding angle while remaining in the radio beacon. If desired, the fieldmay also be equipped with guiding lamps or vertical beacons, i. e.,light beacons that direct light rays upwardly, such as red or dangerlamps l6 and I! located beyond the approach border 3, and green or.

safety lamps I8 and I! located within the runway at a point in which itis safe to contact with the ground. The aircraft, moving along line L,is close to the ground when passing over lamps i6, i1 and l8, l9, andhence the operator can see these lamps in spite of heavy fog. It isdesirable, though not essential, that the aircraft maintain a definitealtitude when approaching the field since, regardless of its altitude,the pilot will be notified at the proper time. i. e., at the time thecraft reaches angle A, to start his descent at the previously givengliding angle so as to land properly on the field. The higher the craft,the sooner it will reach an inclination with respect to the groundobserver equal to angle A, and hence the sooner will the pilot benotified to start his descent.

A slightly different arrangement is shown in Fig. 2 in which the soundlocator is placed at the. boundary line 3 and the radio beacon,transmitter 20 in advance thereof. This arrangement has a slightadvantage over the prior arrangement in that the aircraft would fly in ahigher elevation over the transmitter. As it passes directly over thebeacon, he receives a further signal that he isvapproaching the field bythe temparary silence of his radio direction finding apparatus. Manydifferent arrangements of radio beacon and sound locator will occur tothose skilled in the art.

In accordance with the provisions of the pat-- ent statutes, I haveherein described the principle and operation of my invention, togetherwith the apparatus which I now consider to represent the best embodimentthereof, but I desire to have it understood that the apparatus shown isonly illustrative and that the invention can be carried out by othermeans. Also, while it is designed to use the various features andelements in the combination and relations described, some of these maybe altered and others omitted without interfering with the more generalresults outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure byLetters Patent is:

1. The method of blind landing for radioguided aircraft which consistsin flying the aircraft toward an airport along a vertical directionalradio 'beam, listening to the approach thereof by a sound locator set ata definite angle of elevation at the port, and signalling the aircraftby radio to glide down when the craft crosses the predetermined angle ofelevation of the sound locator.

2. The method of blind landing for radioguided aircraft which consistsin flying the aircraft toward an airport along a vertical directionalradio beam preferably at a predetermined altitude, listening to theapproach thereof by a binaural sound locator having elevation hornsfixed at a predetermined angle of elevation but adjustable in azimuth,and signalling the aircraft by radio to glide down when the receivedsound in the elevation horns shifts from one ear to the other of thelistener.

3. In an airport for blind landings, a vertical directional radio beamtransmitter arranged to be located at the approach side of the field, asound locator set at a definite angle of elevation for locating theapproaching craft, said sound 10-- cator being positioned adjacent saidtransmitter, and radio means for signalling the craft therefrom when theangle of elevation of the craft as determined by the sound locatorreaches a predetermined amount.

4.' In an airport for blind landings, a portable vertical directionalradio beam transmitter arranged to be located at the approach side ofthe field, a portable sound locator for locating the approaching craft,said sound locator being positioned adjacent and to the rear of saidtransmitter, and radio means for signalling the craft therefrom when theangle of elevation of the craft as determined by the sound locatorreaches a predetermined amount.

5. In an airport for blind landings, a local 1 vertical directionalradio beam transmitter arranged to be located at the approach side ofthe field, a sound locator set at a. definite angle of elevation forlocating the approaching craft, said sound locator being positionedadjacent said transmitter; and means forsignalling the craft therefromwhen the angle of elevation of the craft as determined by the soundlocator reaches a predetermined amount.

6. In a system to supplement radio beam control for aircraft in blindlanding, a binaural.

sound locator adapted to be positioned at a predetermined angle ofelevation and directed in azimuth toward the approaching craft, and

radio means whereby the craft may be signalled to descend when itcrosses said elevation angle.

PRESTON R. BASSETI.

